So if I were talking about the effect of e.g. sex as a meta-level innovation, then I would expect e.g. an increase in the total biochemical and morphological complexity that could be maintained - the lifting of a previous upper bound, followed by an accretion of information. And I might expect a change in the velocity of new adaptations replacing old adaptations.
But to get from there, to something that shows up in the fossil record - that's not a trivial step.
I recall reading, somewhere or other, about an ev-bio controversy that ensued when one party spoke of the "sudden burst of creativity" represented by the Cambrian explosion, and wondered why evolution was proceeding so much more slowly nowadays. And another party responded that the Cambrian differentiation was mainly visible post hoc - that the groups of animals we have now, first differentiated from one another then, but that at the time the differences were not as large as they loom nowadays. That is, the actual velocity of adaptational change wasn't remarkable by comparison to modern times, and only hindsight causes us to see those changes as "staking out" the ancestry of the major animal groups.
I'd be surprised to learn that sex had no effect on the velocity of evolution. It looks like it should increase the speed and number of substituted adaptations, and also increase the complexity bound on the total genetic information that can be maintained against mutation. But to go from there, to just looking at the fossil record and seeing faster progress - it's not just me who thinks that this jump to phenomenology is tentative, difficult, and controversial.
Should you expect more speciation after the invention of sex, or less? The first impulse is to say "more", because sex seems like it should increase the optimization velocity and speed up time. But sex also creates mutually reproducing populations, that share genes among themselves, as opposed to asexual lineages - so might that act as a centripetal force?
The idea that the development of sex didn't speed up the process of speciation would, if true, be important for a certain problem I'm currently working on. Could anyone point me towards some sort of academic discussion on the subject?
Today's post, Observing Optimization was originally published on 21 November 2008. A summary (taken from the LW wiki):
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